Hydrogenation catalyst and hydrogenation process wherein said catalyst is used

ABSTRACT

A hydrogenation catalyst prepared by combining a Group VIIIA metal compound and a hydrocarbyl-substituted silicon alumoxane and a hydrogenation process wherein said catalyst is used to hydrogenate compounds containing ethylenic and/or aromatic unsaturation. The Group VIIIA metal compound is selected from the group of compounds consisting of carboxylate, chelates, alkoxides, salts of hydrocarbon acids containing sulfur and salts of partial half esters of hydrocarbyl acids containing sulfur. Nickel, cobalt and palladium compounds are particularly preferred for use in the hydrogenation catalyst. Hydrogenation catalysts prepared with hydrocarbyl-substituted silicon slumoxanes initially exhibit less hydrogenation activity than catalyst known heretofore in the prior art and prepared with a metal alkyl of a metal selected from Groups I, II and III. These catalysts, then, afford greater control over the extent of hydrogenation, particularly when partial hydrogenation is a desired end result. Ultimately, however, the catalyst permits substantially complete hydrogenation of both ethylenic and aromatic unsaturation.

This is a division of application Ser. No. 07/527,924, filed May 24,1990 and now U.S. Pat. No. 5,013,798.

BACKGROUND

1. Field of the Invention

This invention relates to a hydrogenation catalyst and a hydrogenationprocess wherein said catalyst is used. More particularly, this inventionrelates to a hydrogenation catalyst and to a process wherein saidcatalyst is used to saturate ethylenic and/or aromatic unsaturation.

2. Prior Art

Catalyst for hydrogenating chemical compounds containing ethylenicand/or aromatic unsaturation, are, of course, well known in the priorart. Useful catalysts include such heterogeneous catalysts as nickel onkieselguhr, Raney nickel, copper chromate, molybdenum sulfide, finelydivided platinum, finely divided palladium, platinum oxide, copperchromium oxide and the like, as taught, for example, in U.S. Pat. No.3,333,024. Useful catalysts also include homogeneous systems such asthose prepared with rhodium compounds or complexes, as taught, forexample, in U.K. Patent No. 1,558,491 and in U.S. Pat. Nos. 4,581,417and 4,674,627 and those prepared with ruthenium complexes as taught, forexample, in U.S. Pat. No. 4,631,315. As is known in the prior art,certain of these catalysts are quite effective in the hydrogenation ofethylenic unsaturation but many of these catalysts are not selective asbetween ethylenic and aromatic unsaturation and therefore cannot beeffectively used to selectively hydrogenate ethylenic unsaturation in acompound containing both ethylenic and aromatic unsaturation. Catalystswhich are useful in the hydrogenation of ethylenic unsaturation, whichcatalyst may be used selectively as between ethylenic and aromaticunsaturation, include catalysts which are frequently referred to ashomogeneous systems, prepared by combining an iron group metal compound,particularly a nickel or cobalt compound, with a reducing agent. Suchcatalyst may be the reaction product of an iron group metal alkoxide andan aluminum hydrocarbon compound as taught, for example, in U.S. Pat.No. 3,113,986; the reaction product of an iron group metal carboxylate,chelate or alkoxide and a lithium or magnesium hydrocarbon compound astaught, for example, in U.S. Pat. No. 3,541,064; the reaction product ofa nickel or cobalt alkoxide or carboxylate and an aluminum trialkyl astaught, for example, in U.S. Pat. No. 3,700,633 or the reaction productof an iron group carboxylate, an enolate, a phenolate or a salt ofcertain sulfur-containing acids and half esters thereof and a metalalkyl or a metal selected from Groups I, II and III as taught forexample in British Patent Specification 1,030,306. It is also known touse iron group metal compounds containing from about 0.5 to about 1.3mols of water per mole of iron group metal compound in preparingcatalysts of this type. Reducing agents that may be used in preparingcatalysts include metal alkoxides as taught, for example, in U.S. Pat.Nos. 3,412,174 and 4,271,323. As is known in the prior art, thesecatalysts can be used in a manner such that essentially all of anyethylenic unsaturation contained in the chemical compound ishydrogenated while essentially none of the aromatic unsaturationcontained therein is hydrogenated. These catalysts are, however,generally less active than the non-selective catalysts heretofore knownin the prior art, and, as a result, longer holding times are generallyrequired to effect the desired degree of selective hydrogenation.Moreover, most, if not all, of these selective catalysts generallyresult in significant conversion of ethylenic unsaturation in relativelyshort contacting times and then proceed rather slowly with respect tosuch conversion thereafter, thereby preventing good control over theextent of conversion of the ethylenic unsaturation when partialhydrogenation is the desired objective. In light of these deficiencies,then, the need for a catalyst which can be used to selectivelyhydrogenate ethylenic unsaturation in a chemical compound containingboth ethylenic and aromatic unsaturation, which catalyst will provide asgreat an extent of hydrogenation after a reasonable contacting time whencompared to the selective catalyst known in the prior art is believed tobe readily apparent. The need for a catalyst which will afford bettercontrol over the extent of hydrogenation is also believed to be readilyapparent.

SUMMARY OF THE INVENTION

It has now been discovered that the foregoing and other disadvantages ofthe prior art catalyst and processes useful in hydrogenating ethylenicand/or aromatic unsaturation can be overcome or at least significantlyreduced with the catalyst and process of this invention. It is,therefore, an object of the present invention to provide an improvedcatalyst for hydrogenating ethylenic and/or aromatic unsaturation. It isanother object of this invention to provide a hydrogenation processwherein said improved catalyst is used to hydrogenate ethylenic and/oraromatic unsaturation. It is still another object of this invention toprovide such an improved hydrogenation catalyst which can be used toselectively hydrogenate ethylenic unsaturation when aromaticunsaturation is also present. It is a still further object of thisinvention to provide such an improved hydrogenation catalyst which willenable as good an extent of hydrogenation after a reasonable holdingtime as that provided by known selective hydrogenation catalyst. It iseven a further object of this invention to provide certain improvedhydrogenation catalysts which will afford better control over the extentto which the hydrogenation has proceeded. The foregoing and otherobjects and advantages will become apparent from the description setforth hereinafter.

In accordance with the present invention, the foregoing and otherobjects and advantages are accomplished with a catalyst obtained bycontacting one or more Group VIIIA metal compounds and one or morecompounds containing aluminum, silicon, oxygen and hydrocarbyl groups,said compound hereinafter frequently being referred to as a siliconalumoxane compound, and with a process wherein said catalyst is used topartially or completely hydrogenate ethylenic and/or aromaticunsaturation. As used herein, all reference to metals of a specifiedGroup shall be by reference to the Groups as depicted in the PeriodicTable of the Elements by Mendeleev, Long Form, as published inKirk-Othmer Encyclopedia of Chemical Technology, 2nd, 1964, Vol. 8, Page94. As discussed more fully hereinafter, the catalysts of this inventionmay also be used to selectively hydrogenate ethylenic unsaturation in acompound containing both ethylenic and aromatic unsaturation. As alsodiscussed more fully hereinafter, the extent of hydrogenation, initiallyat least, proceeds rather slowly with certain of the catalysts hereincontemplated, thereby making it possible to more accurately control theextent of hydrogenation when partial hydrogenation is a desired result.The catalysts further may be used at more severe hydrogenationconditions so as to hydrogenate both ethylenic and aromatic unsaturationin compounds containing both types of unsaturation.

DETAILED DESCRIPTION OF THE INVENTION

As just indicated supra, the present invention is drawn to a catalystprepared by contacting one or more Group VIIIA metal compounds with oneor more compounds containing silicon, aluminum, oxygen and hydrocarbylgroups and to a hydrogenation process wherein said catalyst is used topartially or completely hydrogenate ethylenic and/or aromaticunsaturation. The catalysts of this invention will, frequently, bereferred to herein as useful to selectively hydrogenate ethylenicunsaturation in a compound containing both ethylenic and aromaticunsaturation. Certain of the catalysts of this invention may further beuseful to more carefully control the extent of hydrogenation in suchcompounds when partial hydrogenation is an objective. The catalyst maystill further be useful, generally, at more severe hydrogenationconditions so as to hydrogenate at least a portion of both the ethylenicand aromatic unsaturation in compounds containing both types ofunsaturation.

In general, any of the Group VIIIA metal compounds known to be useful inthe preparation of catalysts for the hydrogenation of ethylenicunsaturation can be used to prepare the catalyst of this invention.Suitable compounds, then, include Group VIIIA metal carboxylates havingthe formula (RCOO)_(n) M wherein M is a Group VIIIA metal, R is ahydrocarbyl radical having from 1 to about 50 carbon atoms, preferablyfrom about 5 to 30 carbon atoms, and n is a number equal to the valenceof the metal M; Group VIIIA metal chelates containing from about 3 toabout 50 carbon atoms, preferably from about 3 to about 20 carbon atoms;Group VIIIA metal alkoxides having the formula (RCO)_(n) M wherein M isagain a Group VIIIA metal, R is a hydrocarbon radical having from 1 toabout 50 carbon atoms, preferably about 5 to about 30 carbon atoms, andn is a number equal to the valence of the metal M; Group VIIIA metalsalts of sulfur-containing acids having the general formulaM(SO_(x))_(n) and partial esters thereof having the general formulaM(SO_(x) R'_(y))_(n) wherein M is a Group VIIIA metal, x is a wholenumber equal to 2, 3 or 4, y is a whole number at least one less than xequal to 1, 2, or 3, R is a hydrocarbon radical having from 1 to about20 carbon atoms and n is a number equal to the valence of the metal M.Preferably, the Group VIII metal will be selected from the Groupconsisting of nickel, cobalt and palladium, most preferably, the GroupVIIIA metal will be nickel. The carboxylates useful in preparing thecatalyst of this invention include Group VIIIA metal salts ofhydrocarbon aliphatic acids, hydrocarbon cycloaliphatic acids andhydrocarbon aromatic acids. Examples of hydrocarbon aliphatic acidsinclude hexanoic acid, ethylhexanoic acid, heptanoic acid, octanoicacid, nonanoic acid, decanoic acid, dodecanoic acid, myristic acid,palmitic acid, stearic acid, oleic acid, linoleic acid, rhodinic acidand the like. Examples of hydrocarbon aromatic acids include benzoicacid and alkyl-substituted aromatic acids in which the alkylsubstitution has from 1 to about 20 carbon atoms. Examples ofcycloaliphatic acids include naphthenic acid, cyclohexylcarboxylic acid,abietic-type resin acids and the like. Suitable chelating agents whichmay be combined with a Group VIIIA metal thereby yielding a Group VIIIAmetal chelate compound useful in the preparation of the catalyst of thisinvention include β-ketones, α-hydroxycarboxylic acids, β-hydroxycarboxylic acids, β-hydroxycarbonyl compounds and the like. Examples ofβ-ketones which may be used include acetylacetone, 1,3-hexanedione,3,5-nonadione, methyl-aceto acetate, ethyl-aceto acetate and the like.Examples of α-hydroxycarboxylic acid which may be used include lacticacid, glycolic acid, α-hydroxycarboxylic acid, α-hydroxy-α-phenylaceticacid, α-hydroxycyclohexylacetic acid and the like. Examples ofβ-hydroxycarboxylic acids include salicylic acid, alkyl-substitutedsalicyclic acids and the like. Examples of β-hydroxylcarbonyl compoundsthat may be used include salicyl-aldehyde, o-hydroxyacetophenone and thelike. The metal alkoxides which are useful in preparing catalysts ofthis invention include Group VIIIA metal alkoxides of hydrocarbonaliphatic alcohols, hydrocarbon cycloaliphatic alcohols and hydrocarbonaromatic alcohols. Examples of hydrocarbon aliphatic alcohols includehexanol, ethylhexanol, heptanol, octanol, nonanol, decanol, dodecanoland the like. The Group VIIIA metal salts of sulfur-containing acids andpartial esters thereof include Group VIIIA metal salts of sulfonic acid,sulfuric acid, sulphurous acid, partial esters thereof and the like.Aromatic acids such as benzene sulfonic acid, p-toluene sulfonic acidand the like are particularly useful. The Group VIIIA metal compoundsused to prepare the catalysts of this invention may, but need notcontain water. When water is present, the amount of water present mayrange from about 0.5 up to about 1.3 moles of water per mole or atom ofGroup VIIIA metal.

In general, any compound containing one or more silicon atoms and one ormore aluminum atoms, each of said silicon atoms being bonded to eitheranother silicon atom or an aluminum atom either directly or through anoxygen atom and each of said aluminum atoms being bonded to anotheraluminum atom or a silicon atom either directly or through an oxygenatom, and at least one hydrocarbyl or hydrocarbyloxy group bonded toeach silicon atom and at least one aluminum atom, preferably eachsilicon and each aluminum atom, which compound is capable of reducing aGroup VIIIA metal compound useful in preparing the catalyst of thisinvention may be used as the hydrocarbyl-substituted silicon alumoxanecompound in preparing the catalysts of this invention. Usefulhydrocarbyl-substituted silicon alumoxanes, then, include those havingthe following general formula:

1. R¹ R² R³ SiOAlR⁴ R⁵

2. R⁶ R⁷ AlO--SiR⁸ R⁹ O)_(n) SiR¹⁰ R¹¹ --OAlR¹² R¹³)_(p)

3. R¹⁴ R¹⁵ R¹⁶ SiO--AlR¹⁷ O--_(n') AlR¹⁸ --OSiR¹⁹ R²⁰ R²¹)

4. (φ₂ SiOAlR²² O--_(n") AlR²³ R²⁴

5. φ₂ Si--OAlR²⁵ R²⁶)₂

wherein:

n and n' are, independently, numbers ranging from zero to about 20;

n" is a number ranging from about 1 to about 5;

p is a number ranging from 1 to 4; and

each of R¹ -R²⁶, inclusive, are the same or a different radical selectedfrom the group of radical consisting of the hydrogen radical,hydrocarbyl radicals having from 1 to about 20 carbon atoms andhydrocarbyloxy radicals having from 1 to about 20 carbon atoms and from1 to about 5 oxygen atoms with the proviso that at least a sufficientnumber of R¹ R² R³ ; R⁴ R⁵ ; R⁶ R⁷ ; R⁸ R⁹ ; R¹⁰ R¹¹ ; R¹² R¹³ ; R¹⁴ R¹⁵R¹⁶ ; R¹⁹ R²⁰ R²¹ ; R²³ R²⁴ ; R²⁵ R²⁶ ; R¹⁷ ; R¹⁸ and R²² be hydrocarbylor hydrocarbyloxy such that each silicon atom and at least one aluminumatom in the compound have at least one hydrocarbyl or hydrocarbyloxyradical bonded thereto. When an R is hydrocarbyl or hydrocarbyloxy, thesame may be a linear or branched alkyl group, a cycloalkyl oralkyl-substituted cycloalkyl group or an aromatic or alkyl-substitutedaromatic group. It will, of course, be appreciated that when an R iscyclic, it will contain at least 3 carbon atoms and when an R isaromatic, it will contain at least 6 carbon atoms.

Compounds satisfying general formulae 1-3, inclusive, may be preparedusing techniques well known in the prior art. For example, compoundssatisfying general formula 1 may be prepared using processes such asthose described in U.S. Pat. Nos. 3,661,878; 3,969,332; 4,036,867 and4,472,519, the disclosure of which patents are herein incorporated byreference. Compounds satisfying general formula 2 may be prepared usinga process such as that described in U.S. Pat. No. 3,657,159, thedisclosure of which patent is herein incorporated by reference.Compounds satisfying general equation 3, at least when n' is zero, maybe prepared using the method suggested in U.S. Pat. No. 3,969,332.Compounds satisfying general formula 4 may be prepared by reactingdiphenylsilicondiol, φ₂ Si(OH)₂, with a trihydrocarbyl aluminum on anequimolar basis while compounds satisfying general formula 5 may beprepared by reacting these same compounds at a molar ratio of two molesaluminum reactant per mole silicon reactant.

In general, and as suggested supra, the hydrocarbyl-substituted siliconalumoxane compound may contain more silicon atoms than aluminum atoms;more aluminum atoms than silicon atoms, or the same number of siliconand aluminum atoms. Interestingly, it has been discovered that variancein the Si:Al atomic ratio of the hydrocarbyl-substituted siliconalumoxanes used to prepare the catalysts of this invention will vary therate of hydrogenation when the catalyst are used therefor. Moreover, thevariance in hydrogenation rate further varies as a function ofhydrogenation time with each of the possible Si:Al atomic ratios atleast with respect to combinations wherein the Si:Al atomic ratio isgreater than one, equal to one or less than one. For example, when thehydrocarbyl-substituted silicon alumoxane contains: more silicon atomsthan aluminum atoms and particularly a plurality of silicon atoms; e.g.2 or 3 silicon atoms and a single aluminum atom, the initial rate ofhydrogenation will be the slowest, thus affording the maximum amount ofcontrol over the extent of hydrogenation initially, but ultimately isthe fastest, thus permitting complete or at least substantially completehydrogenation in the shortest reaction time; with an equal number ofsilicon atoms and aluminum atoms, particularly one of each, theinitially reaction rate is the fastest of the three possibilities butremains relatively slow for longer hydrogenation times, thus affordingmaximum control over the extent of hydrogenation at intermediateconversions; and with more aluminum atoms than silicon atoms andparticularly a plurality of aluminum atoms; e.g. 2 or 3 aluminum atomsand a single silicon atom, the hydrogenation rate is intermediate ofthese two extremes throughout the hydrogenation reaction.

In general, the actual hydrogenation catalyst will be prepared bycontacting the Group VIIIA metal component with thehydrocarbyl-substituted silicon alumoxane compound in a suitable solventat a temperature within the range from about 20° C. to about 80° C. Ingeneral, the solvent used for preparing the catalyst may be anyone ofthose solvents known in the prior art to be useful as solvents forpreparing unsaturated hydrocarbon polymers. Suitable solvents includealiphatic hydrocarbons such as hexane, heptane, octane and the like;cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane, and thelike; alkyl-substituted cycloaliphatic hydrocarbons such asmethylcyclopentane, methylcyclohexane, methylcyclooctane and the like;aromatic hydrocarbons such as benzene, hydroaromatic hydrocarbons suchas decalin, tetralin and the like; alkyl-substituted aromatichydrocarbons such as toluene, xylene and the like; halogenated aromatichydrocarbons such as chlorobenzene and the like; linear and cyclicethers such as methyl ether, ethyl ether, tetrahydrofuran and the like;and ketones such as methyl ketone (acetone) methylethyl ketone, ethylketone (3-pentanone) and the like. In general, a suitable hydrogenationcatalyst can be prepared by combining the components used to preparecatalyst in a separate vessel prior to feeding the same to thehydrogenation reactor or the separate components can be fed directly tothe hydrogenation reactor when the hydrogenation is accomplished at atemperature at which the separate components will yield an activecatalyst. Preferably, the Group VIIIA metal compound will be combinedwith the hydrocarbyl-substituted silicon alumoxane in a separate vesselprior to feeding the reaction product to the hydrogenation reactor. Ingeneral, the components used to prepare the catalyst will be combined ina ratio sufficient to provide from about 0.5 to about 20 moles or atomsof aluminum per mole or atom of Group VIIIA metal when the catalyst isprepared.

In general, the hydrogenation catalyst of this invention may be used tohydrogenate any hydrocarbon or substituted hydrocarbon containing eitherethylenic unsaturation and/or aromatic unsaturation. The catalyst ofthis invention is particularly useful for the hydrogenation ofhydrocarbon and substituted hydrocarbon polymers. When the hydrocarbonor substituted hydrocarbon polymer to be hydrogenated contains bothethylenic and aromatic unsaturation, the hydrogenation catalyst of thisinvention can be used at catalyst concentrations, hydrogenationtemperatures, hydrogen partial pressures and nominal holding times whichwill enable partial, complete or selective hydrogenation. In thisregard, it will be appreciated that ethylenic unsaturation, particularlythat which does not contain hydrocarbyl-substitution on both of thecarbon atoms contained in the ethylenic unsaturation group willhydrogenate at milder hydrogenation conditions than will aromaticunsaturation. As a result, selective hydrogenation can be accomplishedsuch that at least a portion of the ethylenic unsaturation ishydrogenated while essentially none of the aromatic unsaturation ishydrogenated. In fact, selective hydrogenation can be accomplished withthe hydrogenation catalyst of this invention such that substantially allof the ethylenic unsaturation which does not contain hydrocarbylsubstitution on both of the carbon bonds contained in the ethylenicunsaturation can be saturated while essentially none of the aromaticunsaturation is hydrogenated. At more severe conditions, however, atleast a portion of the aromatic unsaturation will also be hydrogenatedand if contacting is continued for a sufficient period of time at severeenough conditions substantially all of the ethylenic and aromaticunsaturation can be hydrogenated.

The hydrogenation catalyst of this invention may be used to hydrogenateessentially any unsaturated compound including polymers containingethylenic and/or aromatic unsaturation. The hydrogenation catalyst ofthis invention will also hydrogenate any acetylenic unsaturation thatmay be contained in the unsaturated compound. In general, however, andwhile the unsaturated polymer or other hydrocarbon may be substitutedwith various functional groups, the polymers or other hydrocarbonsactually hydrogenated with the hydrogenation catalyst of this inventionshould be essentially free of functional groups that will react with thecatalyst thereby deactivating the same. In general, such groups includeboth those which are strongly acidic (pH≦5) and those which are stronglybasic (pH≧9). The substitutions that may be on the hydrocarbon, then,would be those which, when dissolved in water, would have a pH greaterthan about 5 and less than about 9.

The hydrogenation catalyst of this invention will be particularlyeffective for hydrogenating polymers containing ethylenic unsaturationand/or aromatic unsaturation. As is well known, polymers containingethylenic unsaturation can be prepared by polymerizing one or morepolyolefins, particularly diolefins. The polyolefins may be polymerizedalone or in combination with other vinyl monomers such asalkenylaromatic hydrocarbons, acrylates, methacrylates, vinyl- andallylalcohols, vinyl and allyl ethers, vinyl halides, vinylidenehalides, and the like. Polymers containing aromatic unsaturation may beprepared by polymerizing one or more alkenyl aromatic hydrocarbons. Thealkenyl aromatic hydrocarbons may be polymerized alone or in combinationwith other copolymerizable vinyl monomers such as polyolefins,acrylates, methacrylates, vinyl and allyl ethers, vinyl halides, and thelike to produce polymers containing aromatic unsaturation. As is alsowell known, polyolefins, particularly conjugated diolefins, and alkenylaromatic hydrocarbon, particularly monoalkenyl aromatic hydrocarbons,can be copolymerized to product polymers containing both ethylenic andaromatic unsaturation. The hydrogenation catalyst of this invention maybe used to either partially or substantially completely hydrogenateethylenic unsaturation contained in such a polymer. The hydrogenationcatalyst of this invention may also be used to either partially orcompletely hydrogenate aromatic unsaturation contained in such apolymer. The hydrogenation catalyst of this invention may further beused to selectively hydrogenate ethylenic unsaturation in polymerscontaining both ethylenic and aromatic unsaturation. As used herein, therecitation "selective hydrogenation" shall mean hydrogenationaccomplished such that ethylenic unsaturation is hydrogenated whilearomatic unsaturation is not or at least wherein the relative amount ofethylenic unsaturation hydrogenated is significantly greater than therelative amount of aromatic unsaturation hydrogenated.

As is well known in the prior art, polymers containing ethylenic and/oraromatic unsaturation may be prepared using free-radical, cationic andanionic initiators or polymerization catalysts. Such polymers may alsobe prepared using bulk, solution or emulsion techniques. It is, ofcourse, known in the prior art that all polymers cannot be prepared witheach of these initiators or catalysts and that all polymers cannot beprepared with each of the different techniques. Which polymers may beprepared with the several catalysts and which polymers may be preparedwith the various techniques is, however, well known in the prior art andneed not be discussed herein in detail. As indicated more fullyhereinafter, however, the actual hydrogenation will be accomplished insolution. It is, therefore, important to the hydrogenation method ofthis invention that the unsaturated hydrocarbon or substitutedhydrocarbon be soluble in a solvent.

As indicated supra, the hydrogenation catalyst of this invention isparticularly useful for hydrogenating hydrocarbon polymers containingethylenic and/or aromatic unsaturation. The present invention will,therefore, be described in greater detail by reference to such polymers.It should, however, be kept in mind, as also indicated supra, that anyunsaturated hydrocarbon or substituted-unsaturated hydrocarbon or anyunsaturated polymer which is also soluble in a suitable solvent could besubstituted for the hydrocarbon polymer with which the invention will bedescribed in greater detail. Also, while the polymer actuallyhydrogenated may be prepared using bulk, solution or emulsiontechniques, as indicated supra, the invention is particularly effectivewith polymers prepared in solution since the hydrogenation may beaccomplished immediately after preparation thereof with a reduced numberof steps. Polymers prepared with bulk or emulsion techniques, however,could be recovered and then dissolved in a solvent to effecthydrogenation with the hydrogenation catalyst of this invention.

As is well known, homopolymers of conjugated diolefins, copolymers ofconjugated diolefins and copolymers of one or more conjugated diolefinsand one or more other monomers, particularly a monoalkenyl aromatichydrocarbon monomer, are commonly prepared in solution with an anionicpolymerization initiator and the hydrogenation catalyst of thisinvention is particularly effective in both the partial, complete andselective hydrogenation of such polymers. As is well known, suchpolymers may be random, tapered, block, branched or radial. In general,polymers of this type are prepared by contacting the monomer or monomersto be polymerized with an organoalkali metal compound in a suitablesolvent at a temperature within the range from about -150° C. to about300° C., preferably at a temperature within the range from about 0° C.to about 100° C. When the polymer is to be tapered, all of the monomersto be contained in the polymer are, frequently, introduced together atthe beginning of the polymerization. When the polymer is to be random, arandomizing agent may generally be used. When the polymer is to be alinear block, the monomers are, generally, polymerized sequentially andwhen the polymer is to be a radial polymer, the polymeric arms are firstprepared and then coupled with a satisfactory coupling agent.Particularly effective anionic polymerization initiators areorganolithium compounds having the general formula:

    RLi.sub.n

wherein: R is an aliphatic, cycloaliphatic, aromatic oralkyl-substituted aromatic hydrocarbon radical having from 1 to about 20carbon atoms; and n is an integer of 1 to 4.

Conjugated diolefins which may be polymerized separately or incombination anionically include those conjugated diolefins containingfrom 4 to about 12 carbon atoms such as 1,3 butadiene, isoprene,piperylene, methylpentadiene, phenylbutadiene,3,4-dimethyl-1,3-hexadiene, 4,5-diethyl-1,3-octadiene and the like.Conjugated diolefins containing from 4 to about 6 carbon atoms are,preferably, used in such polymers and conjugated diolefins containing 4or 5 carbon atoms are most preferably used in such polymers. Theconjugated diolefin polymers prepared via anionic initiation may containone or more other monomers, particularly a monoalkenyl aromatichydrocarbon monomer. Suitable monoalkenyl aromatic hydrocarbon monomersinclude styrene, various alkyl-substituted styrenes, alkoxy-substitutedstyrenes, vinyl naphthalene, alkyl-substituted vinyl naphthalenes andthe like. Conjugated diolefin polymers which may be hydrogenated withthe hydrogenation catalyst of the present invention include thosehomopolymers and copolymers described in U.S. Pat. Nos. 3,135,716;3,150,209; 3,496,154; 3,498,960; 4,145,298 and 4,238,202, the disclosureof which patents are herein incorporated by reference. Conjugateddiolefin polymers which may be partially, completely or selectivelyhydrogenated with the hydrogenation catalyst of this invention alsoinclude block copolymers such as those described in U.S. Pat. Nos.3,231,635; 3,265,765 and 3,322,856, the disclosure of which patents arealso incorporated herein by reference. In general, linear blockcopolymers which may be hydrogenated in accordance with the presentinvention may be represented by the general formula:

    A.sub.z --(B--A).sub.y --B.sub.x

wherein:

A is a polymeric block comprising predominantly monoalkenyl aromatichydrocarbon monomer units;

B is a polymeric block containing predominantly conjugated diolefinmonomer units;

x and z are, independently, a number equal to 0 or 1; and

y is a whole number ranging from 1 to about 15.

Conjugated diolefin polymers which may be partially, completely orselectively hydrogenated with the hydrogenation catalyst of thisinvention further include radial block copolymers such as thosedescribed in U.S. Pat. Nos. 4,033,888; 4,077,893; 4,141,847; 4,391,949and 4,444,953, the disclosure of which patents are also incorporatedherein by reference. Radial block copolymers which may be hydrogenatedwith the hydrogenation catalyst of the present invention may berepresented by the general formula:

    [A.sub.z --(B--A).sub.y --B.sub.x ].sub.n --C--P.sub.n'

wherein:

A, B, x, y and z are as previously defined;

n is a number from 3 to about 30;

c is the core or nucleus of the radial polymer formed with apolyfunctional coupling agent;

Each P is the same of a different polymer block or polymer segmenthaving the general formula:

    A'.sub.x' --(A"--B').sub.z' --B".sub.y'

wherein:

A' is a polymer block or segment comprising predominantly monoalkenylaromatic hydrocarbon monomer units which may be the same or differentfrom A and A" when A" is block;

(A"--B")₋₋ is a polymer block or segment containing monoalkenyl aromatichydrocarbon monomer units, A", and conjugated diolefin monomer units,B', wherein the A"--B' monomer units may be random, tapered or block andwhen block, A" may be the same or different from A and A' and B' may bethe same or different from B and B";

B" is a polymer block or segment comprising prediminantly conjugateddiolefin monomer units;

x' and z' are independently numbers equal to 0 or 1;

z' is a whole number ranging from 0 to about 15 and

n' is a whole number ranging from 1 to about 30.

In general, hydrogenation of the unsaturated polymer with thehydrogenation catalyst of this invention may be accomplished in any ofthe solvents useful for preparing such polymers known in the prior art.Such solvents include straight- and branched-chain aliphatichydrocarbons, cycloaliphatic hydrocarbons, alkyl-substitutedcycloaliphatic hydrocarbons, aromatic hydrocarbons, alkyl-substitutedaromatic hydrocarbons, linear and cyclic ethers, ketones and the like aspreviously described. In general, the solution of polymer and solventwill contain from about 1 wt % to about 30 wt % polymer and from about99 wt % to about 70 wt % solvent.

In general, the hydrogenation will be accomplished at a temperaturewithin the range from about 20° C. to about 175° C. at a hydrogenpartial pressure within the range from about 50 psig to about 5,000psig, preferably at a hydrogen partial pressure of 50 to 3000 psig andmost preferably at a hydrogen partial pressure within the range fromabout 50 to about 950 psig. In general, the catalyst or the componentsthereof will be added in a concentration sufficient to provide fromabout 0.2 to about 100 mmoles of Group VIIIA metal per lb of polymer orother compound being hydrogenated. In general, contacting athydrogenation conditions will be continued for a nominal holding timewithin the range from about 10 to about 360 minutes. It will, of course,be appreciated that the more severe hydrogenation conditions at longernominal holding times will, generally, result in complete or nearcomplete hydrogenation of the polymer while milder hydrogenationconditions and shorter holding times favor partial hydrogenation and maybe used to effect selective hydrogenation as between ethylenic andaromatic unsaturation. Of the several variables available to control theextent of hydrogenation, temperature and catalyst concentration andnominal holding time, generally, have the greatest affect on the extentof hydrogenation, particularly where selective hydrogenation is thedesired result. Hydrogen partial pressure, on the other hand, generally,has a lesser affect on severity as well as selectivity as between thehydrogenation of ethylenic unsaturation and hydrogenation of aromaticunsaturation. Nominal holding time will, of course, significantly affectthe extent of hydrogenation in those cases where partial hydrogenationof either ethylenic unsaturation or aromatic unsaturation is the desiredresult.

In general, selective hydrogenation as between ethylenic and aromaticunsaturation will be accomplished at a temperature within the range fromabout 20° to about 100° C. at a total pressure within the range fromabout 100 to about 1,000 psig at a hydrogen partial pressure within therange from about 50 to about 950 psig and at a catalyst concentrationwithin the range from about 0.4 to about 40 mmoles of Group VIIIA metalper pound of polymer or other compound being hydrogenated. Nominalholding times within the range from about 30 to about 240 minutes will,generally, be used to effect selective hydrogenation. In general, thehydrogenation catalyst of this invention can be used to effectsubstantially complete hydrogenation of any ethylenic unsaturationcontained in a polymer without effecting any hydrogenation of anyaromatic unsaturation contained in the same polymer. Partialhydrogenation of the ethylenic unsaturation in such a polymer can, ofcourse, be accomplished by reducing the nominal holding time, thetemperature, the catalyst concentration and/or the hydrogen partialpressure. In general, partial, complete and/or selective hydrogenationwill be accomplished without any significant degradation of the polymer.

While the inventor does not wish to be bound by any particular theory,it is believed that when the components used to prepare thehydrogenation catalyst of this invention are combined a reaction occursto form a catalyst. The catalyst thus formed is stable and can be storedfor relatively long periods prior to use.

After hydrogenation of the polymer has been completed, the polymer maybe recovered as a crumb using techniques well known in the art such asby adding a polar compound such as a ketone, alcohol or the like to thepolymer solution thereby precipitating the polymer as a crumb.Alternatively, the solution may be contacted with steam or hot water andthe solvent then removed by azeotropic distillation. Generally, theserecovery techniques will also effectively remove a significant portionof the catalyst. To the extent that further catalyst removal is desired,however, methods well known in the prior art may be used. In general, asignificant portion of the catalyst residue may be separated bycontacting the polymer or polymer solution with a dilute acid.

The hydrogenated polymers produced by the method of this invention canbe used in any of the applications well known in the prior art for suchhydrogenated polymers. For example, hydrogenated conjugated diolefinpolymers will have improved green strength and cold flow properties andmay be used in as VI improvers, impact modifiers, in adhesivecompositions and the like. Similarly, selectively hydrogenatedconjugated diolefin-monoalkenyl aromatic hydrocarbon polymers may beused in various molding compositions, in adhesives compositions, as VIimprovers, as impact modifiers and the like.

PREFERRED EMBODIMENT OF THE INVENTION

In a preferred embodiment of the present invention, a nickel carboxylateor alkoxide having from about 5 to about 30 carbon atoms, mostpreferably 5 to about 15 carbon atoms, will be combined with analkyl-substituted silicon alumoxane compound containing silicon atomsand aluminum atoms to produce a hydrogenation catalyst. In the preferredembodiment, each of the alkyl groups of the alkyl-substituted siliconalumoxane may be the same or different and each will contain from about1 to about 10 carbon atoms. The contacting between the components usedto prepare the catalyst will be accomplished at a temperature within therange from about 25° C. to about 60° C. in a cycloaliphatic hydrocarbonsolvent. In the preferred embodiment, the contacting will beaccomplished at an Al:Ni atomic ratio within the range from about 1:1 toabout 10:1 on a mole or atom basis and at an Si to Al mole ratio withinthe range from about 0.1 to about 10. In a more preferred embodiment ofthe present invention, a nickel carboxylate will be used and the nickelcarboxylate will be selected from the group consisting of nickel octoateand nickel ethylhexanoate. In a most preferred embodiment, thealkyl-substituted silicon alumoxane compound will contain a plurality ofsilicon atoms and in an even more preferred embodiment 2 or 3 siliconatoms, and a single aluminum atom. In a preferred process embodiment ofthe present invention, the preferred catalyst will be used toselectively hydrogenate a block copolymer comprising at least onepolymeric block containing predominantly mono-alkenyl aromatichydrocarbon monomer units and at least one polymeric block containingpredominantly conjugated diolefin monomer units. The recitationpredominantly as used herein in connection with polymer blockcomposition shall mean that the specified monomer or monomer types isthe principal monomer or monomer type (at least about 85 wt %) containedin that polymer block. Other copolymerizable monomer units may, however,be present. In the preferred embodiment, the monoalkenyl aromatichydrocarbon polymer blocks will have a weight average molecular weightwithin the range from about 5,000 to about 40,000 and the conjugateddiolefin polymer blocks will have a weight average molecular weightwithin the range from about 25,000 to about 125,000. In a preferredprocess embodiment, the hydrogenation will be accomplished in acycloaliphatic hydrocarbon solvent, the solution containing from about10 to about 25 wt % polymer and from about 95 to about 75 wt % solvent.In the preferred process embodiment, the hydrogenation will beaccomplished at a temperature within the range from about 20° to about100° C. at a total pressure within the range from about 100 to about1,000 psig and at a hydrogen partial pressure within the range fromabout 50 to about 950 psig and at a catalyst concentration within therange from about 2 to about 10 mmoles of Ni per pound of polymer. In amost preferred process embodiment, the hydrogenation conditions will becontinued for a nominal holding time within the range from about 30 toabout 180 min. In the preferred process embodiment, the selectivehydrogenation will be accomplished so as to hydrogenate at least 80% ofthe ethylenic unsaturation initially contained in the polymer and lessthan about 5% of the aromatic unsaturation contained therein. In a mostpreferred process embodiment, the most preferred catalyst will be usedand the selective hydrogenation will be accomplished so as tohydrogenate at least 90% of the ethylenic unsaturation initiallycontained in the polymer while hydrogenating essentially none of thearomatic unsaturation contained therein.

Having thus broadly described the present invention and a preferred andmost preferred embodiment thereof, it is believed that the inventionwill become even more apparent by reference to the following Examples.It will be appreciated, however, that the examples are presented solelyfor purposes of illustration and should not be contstrued as limitingthe invention unless one or more of the limitations specificallyintroduced in the Examples are incorporated into the claims appendedhereto.

EXAMPLE 1

In this Example, a hydrogenation catalyst was prepared by combiningtriethylsilicon diethylalumoxane with nickel-2-ethylhexanoate incyclohexane at a temperature of 25° C. The nickel-2-ethylhexanoatecontained about 0.5 moles H₂ O per mole of nickel-2-ethylhexanoate. Inpreparing the catalyst in this Example, the amount of alumoxane combinedwith nickel-2-ethylhexanoate was controlled so as to produce ahydrogenation catalyst with a mixture having an Al:Ni ratio of 3:1. Forconvenience, this catalyst will be referred to hereinafter as catalystNo. 1. This catalyst was used shortly after preparation to hydrogenate ablock copolymer as summarized in Example 3. Surprisingly, this catalystappeared to be truly homogeneous.

EXAMPLE 2

In this Example, a catalyst was prepared by combining anickel-2-ethylhexanoate identical to that used in Example 1 withtriethyl aluminum in cyclohexane at a temperature of 25° C. In preparingthis catalyst, the nickel-2-ethylhexanoate and triethyl aluminum werecombined in an Al:Ni atomic ratio of 2.2:1. This catalyst which ishereinafter referred to as catalyst No. 2, was used shortly afterpreparation to hydrogenate a block copolymer as summarized in Example 4.

EXAMPLE 3

In this Example, the catalyst prepared in Example 1 (Catalyst No. 1) wasused to hydrogenate a linear triblock copolymer comprising terminalpolystyrene blocks and a central butadiene polymer block, eachpolystyrene block having a weight average molecular weight of 7,000 andthe polybutadiene block having a weight average molecular weight of40,000. In the hydrogenation run, the polymer was dissolved incyclohexane, the solution containing 20 wt % polymer and 80 wt %cyclohexane. In the run, 450 grams polymer solution (90 g of polymer)was charged to an autoclave, the contents of the autoclave blanketedwith hydrogen at a hydrogen pressure of about 900 psig and the contentsof the autoclave then heated to 70° C. A sufficient amount of catalystin 50 g cyclohexane was then injected into the autoclave to provide 100ppm Ni, by weight, based on total solution. After the catalyst wasinjected, the reaction medium was raised to a temperature of 90° C. Thecontents of the autoclave were then held at these conditions for threehours while maintaining a hydrogen partial pressure of 900 psig. Asample of the reaction medium was withdrawn from the reactor after 15minutes, 30 minutes, 60 minutes, 2 hours and at completion of the runand analyzed to determine the % of the initial ethylenic unsaturationwhich had been saturated. The extent of hydrogenation was determinedusing an ozone titration. Contacting between the polymer and the ozonewas accomplished at 25° C. In this method, the amount of ozone actuallyreacting with the polymer is determined and this value then used todetermine the amount of ethylenic unsaturation remaining. The resultsactually achieved in the run is summarized in the Table followingExample 4.

EXAMPLE 4

In this Example, the catalyst prepared in Example 2 (Catalyst No. 2) wasused to selectively hydrogenate a triblock copolymer identical to thatused in Example 3. The hydrogenation in the run completed in thisExample was completed at conditions identical to those used in Example 3except that a different catalyst was used. The results obtained withthis catalyst are summarized in the following Table.

                  TABLE                                                           ______________________________________                                               Al:Ni                                                                  Catalyst                                                                             Atomic  % Initial ethylenic unsat. converted after                     No.    Ratio   15 min  30 min                                                                              60 min                                                                              120 min                                                                              180 min                             ______________________________________                                        1        3:1   54.7    74.5  85.3  90.3   92.2                                2      2.2:1   66.4    83.0  88.5  92.7   93.4                                ______________________________________                                    

As will be apparent from the data summarized in the preceding Table, thecatalyst of this invention, is about equivalent to a well known priorart catalyst which is used commercially to selectively hydrogenatestyrene-butadiene and styrene-isoprene block copolymers except that theparticular catalyst within the scope of the present invention used inExample 3 was, initially less active than the prior art catalyst. Thisfeature of this particular hydrogenation catalyst will, then, permit farmore effective control of partial hydrogenation when this is a desiredend result. In this regard, it should be noted that 66.4 of the initialethylenic unsaturation is converted with catalyst 2 after only 15minutes and 83% is converted after 30 minutes while the conversion withthe catalyst of this invention is only 54.7% after 15 minutes and 74.5%after 30 minutes.

EXAMPLE 5

In this Example, a different hydrogenation catalyst within the scope ofthis invention was prepared using the same method as was used inExample 1. This catalyst, which catalyst is hereinafter referred to asCatalyst No. 3, was prepared by contacting (Et₂ AlO)₂ SiO₂ with anickel-2-ethylhexanoate identical to that used in Example 1. The atomicratio of aluminum to nickel was maintained at 3:1 in preparing thiscatalyst.

EXAMPLE 6

In this Example, the catalyst prepared in Example 5 was used toselectively hydrogenate a triblock copolymer identical to that used inExample 3 at the same conditions as were used in Example 3. As inExample 3, samples were withdrawn at 15, 30, 60, 120 and 180 minutes andthe extent of hydrogenation determined on each sample using ozone. Theresults obtained are summarized in the following Table:

                  TABLE                                                           ______________________________________                                               Al:Ni   % Ethylenic unsaturation                                       Catalyst                                                                             Atomic  converted after                                                No.    Ratio   15 min  30 min                                                                              60 min                                                                              120 min                                                                              180 min                             ______________________________________                                        3      3:1     49.0    81.7  91.5  93.2   94.3                                ______________________________________                                    

As will be apparent from the data summarized in the preceding Table, theinitial activity of the catalyst used in this Example was less even thanthat of the catalyst prepared in Example 1 (cf. the conversion after 15minutes). After 30 minutes, however, the activity of this catalyst wasnearly equal to the activity of a prior art catalyst prepared withtriethylaluminum (cf. Catalyst No. 2 of Example 4 with Catalyst No. 3).After 60, 120 and 180 minutes, however, the catalyst tested in thisExample was more active than the prior art catalyst (Catalyst No. 2).

EXAMPLE 7

In the Example, a hydrogenation catalyst within the scope of thisinvention was prepared in a manner identical to that summarized inExample 1 except that EtAl(OsiEt₃)₂ was substituted for the Et₃ SiOAlEt₂used therein. Again, the Al:Ni atomic ratio was controlled at 3:1 duringpreparation of the catalyst. This catalyst was used shortly afterpreparation to hydrogenate a triblock copolymer as summarized in Example8. For convenience, this catalyst is herein referred to as Catalyst No.4.

EXAMPLE 8

In this Example, the catalyst prepared in Example 7, Catalyst No. 4, wasused to selectively hydrogen a polymer identical to that hydrogenated inExample 3. The hydrogenation conditions used were identical to thosesummarized in Example 3 except that the different catalyst was used.Again, samples were taken at 15, 30, 60, 120 and 180 minutes and theextent of hydrogenation determined for each sample in the same manner aswas used in Example 3. The results obtained are summarized in thefollowing Table:

                  TABLE                                                           ______________________________________                                               Al:Ni                                                                  Catalyst                                                                             Atomic  % Initial --(--c═c--)-- converted after                    No.    Ratio   15 min  30 min                                                                              60 min                                                                              120 min                                                                              180 min                             ______________________________________                                        4      3:1     41.8    81.5  92.5  94.9   95.6                                ______________________________________                                    

As will be apparent from the data summarized in the previous Table,Catalyst 4, which was prepared with a hydrocarbyl substituted siliconalumoxane containing Si and Al atoms in a ratio of 2:1 was, initially,less active than Catalyst No. 3, which was prepared with asilicon-aluminum compound containing silicon and aluminum atoms in aratio of 1:2, and Catalyst No. 1 which was prepared with asilicon-aluminum compound containing silicon and aluminum atoms in aratio of 1:1 (cf. the conversion at 15 min.), but ultimately gave thebest total conversion (cf. the conversion after 180 min., for example).Catalyst No. 4 also was intially less active than the prior artcatalyst, Catalyst No. 2, (cf. the conversions at 15 and 30 minutes),but ultimately became more active than this prior art catalyst (cf. allconversions at holding times greater than 30 minutes).

EXAMPLE 9

In this Example, a catalyst within the scope of this invention, whichcatalyst is hereinafter referred to as Catalyst No. 5, was prepared bycombining nickel-2-ethylhexanoate containing 0.5 moles of water per moleof ethylhexanoate with (Me₂ SiO)₃ in an amount sufficient to provide aSi:Ni atomic ratio of 3:1 in cyclohexane to form a precatalyst, thenthis reaction product was reacted with triethyl aluminum in an amountsufficient to provide an Al:Ni atomic ratio of 2:1 in cyclohexane toform the final catalyst. Immediately after preparation, the finalcatalyst was introduced into an autoclave containing an amount ofpolymer, identical to that hydrogenated in Examples 3, 4, 6 and 8, andthe same amount of cyclohexane. The polymer hydrogenated was alsoidentical to that hydrogenated in the previous Examples. The contents ofthe autoclave were at 70° C. and under 900 psig hydrogen and contained asufficient amunt of Ni to provide 100 ppm Ni based on the total amountof polymer and cyclohexane. Immediately after introduction of the finalcatalyst, the temperature of the contents of the autoclave were raisedto 90° C. Samples of the polymer were then withdrawn from the autoclaveat 30, 60, 120 and 180 minutes and the extent of hydrogenation for eachsample then determined using the same method as is summarized in Example3. The results actually obtained on each sample are summarized in thefollowing Table:

                  TABLE                                                           ______________________________________                                        Catalyst                                                                             Al:Ni Atomic                                                                             % --c═c-- conversion after                              No.    Ratio      30 min   60 min                                                                              120 min                                                                              180 min                               ______________________________________                                        5      --         39.3     64.4  90.9   94.8                                  ______________________________________                                    

As will be apparent from the data summarized in the preceding Table, thecatalyst prepared in this Example, Catalyst No. 5, was significantlyless active than any of the previously tested catalysts, even after 60minutes, but ultimately this catalyst permitted very good overallconversion (cf. the conversion of all catalysts at 180 min.). Thissignificant reduction in initial activity is attributed in part to theSi:Al atomic ratio (3:2) of the hydrocarbyl-substituted siliconalumoxane used to prepare the catalyst and perhaps partly to the factthat the catalyst was prepared by combining the components in adifferent order.

The data presented in all of the preceding Examples clearly support theconclusions that (1) catalyst prepared with a hydrocarbyl-substitutedsilicon alumoxane containing more silicon atom than aluminum atomsafford the greatest reduction in initial hydrogenation activity butultimately the greatest extent of hydrogenation; (2) catalyst preparedwith hydrocarbyl-substituted silicon alumoxanes having the same numberof Si and Al atoms reduce the initial activity the least of any of thesilicon-aluminum compounds but retain the reduction in activity forlonger reaction times and (3) catalyst prepared with silicon-aluminumcompounds having more Al atoms than Si atoms are intermediate of thesetwo extremes. These differences in catalysts can, then, be used as anaid in selecting a catalyst to be used to effect partial hydrogenationas well as an aid in selecting the best catalyst for achieving completeor substantially complete conversion.

While the present invention has been described and illustrated byreference to particular embodiments thereof, it will be appreciated bythose of ordinary skill in the art that the same lends itself tovariations not necessarily desribed or illustrated herein. For thisreason, then, reference should be made solely to the appended claims forpurposes of determining the true scope of the present invention.

Having thus described and illustrated the present invention, what isclaimed is:
 1. A catalyst prepared by contacting a Group VIIIA metalcompound with a hydrocarbyl-substituted silicon alumoxane.
 2. Thecatalyst of claim 1 wherein said Group VIIIA metal compound is selectedfrom the group consisting of metal carboxylates, metal alkoxide, metalchelates, metal salts of hydrocarbyl sulfur-containing acids and metalsalts of hydrocarbyl sulfur-containing acid partial esters.
 3. Thecatalyst of claim 2 wherein said Group VIIIA metal compound is a metalcarboxylate.
 4. The catalyst of claim 3 wherein said Group VIIIA metalcarboxylate contains from 1 to about 50 carbon atoms.
 5. The catalyst ofclaim 2 wherein said Group VIIIA metal compound and saidhydrocarbyl-substituted silicon alumoxane are combined in a ratiosufficient to provide an aluminum to Group VIIIA metal atomic ratiowithin the range from about 0.5:1 to about 20:1.
 6. The catalyst ofclaim 5 wherein said Group VIIIA metal is selected from the groupconsisting of cobalt, nickel and palladium.
 7. The catalyst of claim 6wherein said Group VIIIA metal is nickel.
 8. The catalyst of claim 7wherein said Group VIIIA metal compound is nickel-2-ethylhexanoate. 9.The catalyst of claim 2 wherein said Group VIIIA metal compound is analkoxide.
 10. The catalyst of claim 9 wherein said Group VIIIA metal isnickel.
 11. The catalyst of claim 1 wherein said hydrocarbyl-substitutedsilicon alumoxane contains more Si atoms than Al atoms.
 12. The catalystof claim 11 wherein said hydrocarbyl-substituted silicon alumoxanecontains a plurality of silicon atoms and a single aluminum atom. 13.The catalyst of claim 1 wherein said hydrocarbyl-substituted siliconalumoxane contains more aluminum atoms than silicon atoms.
 14. Thecatalyst of claim 13 wherein said hydrocarbyl-substituted siliconalumoxanes contains a plurality of aluminum atoms and a single siliconatom.
 15. The catalyst of claim 1 wherein said hydrocarbyl-substitutedsilicon alumoxane contains the same number of aluminum atoms and siliconatoms.
 16. The catalyst of claim 15 wherein said hydrocarbyl-substitutedsilicon alumoxane contains a single aluminum atom and a single siliconatom.
 17. The catalyst of claim 1 wherein said Group VIII metal compoundand said hydrocarbyl-substituted silicon alumoxane are contacted at aconcentration sufficient to provide an Al:Group VIII metal atomic ratiowithin the range from about 0.5:1 to about 20:1.
 18. The catalyst ofclaim 17 wherein said Group VIII metal compound and saidhydrocarbyl-substituted silicon alumoxane are contacted at aconcentration sufficient to provide an Al:Group VIII metal atomic ratiowithin the range from about 1:1 to about 10:1.